Entamoebidae

A family of amoeboid protozoa

Entamoeba histolytica, a pathogenic species of Entamoebidae

The Entamoebidae are a family of amoeboid protozoa within the order Amoebida. This family includes several genera, with the most notable being Entamoeba, which contains species that are important to human health.

Characteristics

Members of the Entamoebidae family are characterized by their amoeboid movement and their ability to form cysts as part of their life cycle. These organisms are typically found in the gastrointestinal tract of their hosts, where they can exist as either commensals or pathogens.

Morphology

Entamoebidae species exhibit a simple morphology, lacking cilia or flagella. They move and feed using pseudopodia, which are temporary projections of their cytoplasm. The cysts formed by these organisms are typically spherical and contain one or more nuclei, depending on the species.

Life Cycle

The life cycle of Entamoebidae involves two main stages: the trophozoite stage and the cyst stage. The trophozoite is the active, feeding stage, while the cyst is the dormant, resistant stage that can survive outside the host.

Trophozoite Stage

In the trophozoite stage, the amoeba is motile and feeds on bacteria and host cells. This stage is responsible for the symptoms of amoebiasis in pathogenic species such as Entamoeba histolytica.

Cyst Stage

The cyst stage is crucial for transmission. Cysts are excreted in the feces of the host and can survive in the environment until they are ingested by a new host. Upon ingestion, the cysts excyst in the intestine, releasing trophozoites that colonize the gut.

Pathogenic Species

The most well-known pathogenic species within the Entamoebidae family is Entamoeba histolytica, which causes amoebic dysentery and liver abscesses in humans. This species is a significant public health concern in many developing countries.

Non-Pathogenic Species

Other species within the genus Entamoeba, such as Entamoeba dispar and Entamoeba coli, are generally non-pathogenic and exist as commensals in the human gut.

Related pages

• Amoebiasis
• Protozoa
• Parasitology